At present, inspection/measurement devices of the scanning electron microscope (hereinafter referred to as SEM) type are used in manufacturing lines of semiconductors. These inspection/measurement devices, for inspecting/measuring dimensions of a circuit pattern formed on a wafer, are playing a key role in improvement in the manufacturing yields of manufacturing lines. Further, these inspection/measurement devices are required to observe as many measurement points as possible in a short time. Thus, speeding up the processing power of these devices leads to an increase in production efficiency of semiconductors.
On the other hand, with the miniaturization of semiconductor patterns and the shift to three-dimensional device structure, it is becoming more and more difficult to obtain a high-contrast of the observed part and that is hindering the observation. The contrast of the sample observed by using an electron beam is formed in a state as a mixture of multiple types of information on the material, the electric potential and the shape of the sample. These situations occur because the amount of generation, the emission angle and the emission energy of secondary electrons or backscattered electrons generated from the sample change depending on the material, the electric potential and the shape of the sample and primary electron irradiation conditions (the number of incident electrons per unit time, the incidence angle and the incidence energy). To put it the other way round, the contrast of the part that should be observed can be enhanced by optimizing the primary electron irradiation conditions and properly selecting the emission angle and energy of the secondary electrons or backscattered electrons.
Especially, with an energy filter for selecting an energy range of electrons to be detected, various types of observations can be made possible by increasing its filtering performance (energy resolution). However, the increase in the energy resolution is accompanied by higher susceptibility to fluctuation in the surface potential of the sample. Consequently, the image contrast becomes unstable. Further, other problems also arise such as changes in the filtering property when a plurality of positions on the same sample are observed. In regard to this problem, Patent Document 1 proposes energy filter adjustment performed before the measurement by setting a filtering property calibration point in the sample.